1. Field of the Invention
The present invention relates to a communication apparatus that uses a spread coding system for a communication system, a communication method of the communication apparatus, and a program that is; executed by a computer mounted on a communication apparatus.
2. Description of Related Art
As a radio communication system, the ultra wide band (UWB) communication system is known. The ultra wide band communication system has attracted attention as a technique that can transmit very short pulses having a period of 1 nanosecond or less, namely at a very high speed of 100 Mbps or more. Since transmission pulses of the ultra wide band communication system are very short, it is known that one pulse has a very large bandwidth of around several GHz on the frequency axis. Thus, the FCC (Federal Communications Commission) of the United States prescribes a spectrum mask for an ultra wide band communication. This provision limits the band for ultra wide band communication system to a range from 3.1 GHz to 10.6 GHz. The provision also states output levels that are limited to room environments. At present, the standardization committee for IEEE 802.15.3a is studying two ultra wide band communication systems. These systems are multi-band orthogonal frequency division multiplex (MB-OFDM) and direct sequence spread spectrum (DS-SS). Each of these systems uses a plurality of sub bands into which a band designated by the FCC is divided. Technical information of the related art of the present patent application is as follows:
[Non-patent document 1] AnujBatara, “15-03-0268-04-003a-Multiband-OFDM-CFP-Document-v0.doc,” [online], Internet <URL: http://www.multibandofdm.org/ieee_proposal_spec.html, March 2004>
[Non-patent document 2] Reed Fisher, Ryuji Kohno, et. al., “15-04-0137-01-003a-merger2-proposal-ds-uwb-update.doc”, [online], March 2004, Internet <URL: ftp://ieee:wireless@ftp.802wirelessworld.com/15/04/15-04-0137-01-003a-merger2-proposal-ds-uwb-update.doc>
At present, there are possibilities of which both the systems will be standardized. However, if different physical layers coexisted, they would interfere with each other and disturb communications. This technical problem would occur between other communication standards besides IEEE 802.15.3a.